all: Rename the tool to kdumpst

Big but self-explanatory commit: rename the tool. The name choice was
kdumpst, since it's a tool to enable both kdump and pstore setting, also
it's a silly wordplay with the superlative of kdump, as in "kdumpest".

It's an invasive change (touches most of the files), but should
offer no functional change other than logging messages showing
kdumpst now, instead of kdump, and some filenames.

Notice it doesn't touch documentation, which will be done in
a subsequent commit.

Signed-off-by: Guilherme G. Piccoli <gpiccoli@igalia.com>

kdumpst-init.service

@@ -0,0 +1,18 @@
+#  SPDX-License-Identifier: LGPL-2.1+
+#
+#  Copyright (c) 2021 Valve.
+#  Maintainer: Guilherme G. Piccoli <gpiccoli@igalia.com>
+#
+
+[Unit]
+Description=kdumpst loader boot-time service
+
+[Service]
+Type=oneshot
+StandardOutput=journal
+ExecStartPre=/usr/lib/kdumpst/kdumpst-load.sh load
+ExecStart=/usr/lib/kdumpst/save-dumps.sh
+RemainAfterExit=yes
+
+[Install]
+WantedBy=basic.target